Boss seal for composite overwrapped pressure vessel

ABSTRACT

A pressure vessel is disclosed. The pressure vessel may include a boss, a liner, an O-ring, and a composite overwrap of shell. A boss may comprise a through aperture, a first groove encircling the through aperture, and a first engagement mechanism. A liner may comprise an interior surface, exterior surface, and a second engagement mechanism. The interior surface may define an interior cavity of the pressure vessel. The second engagement mechanism may mechanically engage the first engagement mechanism to secure the liner to the boss. An O-ring may be positioned within the first groove of the boss and abut the exterior surface of the liner. A composite overwrap may surround the liner and at least a portion of the boss.

RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.13/686,913 filed Nov. 27, 2012, which claims the benefit of U.S.Provisional Patent Application Ser. No. 61/672,217 filed Jul. 16, 2012and U.S. Provisional Patent Application Ser. No. 61/674,263 filed Jul.20, 2012.

U.S. patent application Ser. No. 13/686,913, U.S. Provisional PatentApplication Ser. No. 61/672,217, U.S. Provisional Patent ApplicationSer. No. 61/674,263, as well as U.S. Pat. No. 5,429,845 issued Jul. 4,1995 are each hereby incorporated by reference.

BACKGROUND The Field of the Invention

This invention relates to pressure vessels and, more particularly, tonovel systems and methods for composite overwrapped pressure vessels.

3. The Background Art

The development of advanced composite materials has enabled thedevelopment of lightweight pressure vessels with composite overwrapmaterial. There are several different classifications of these pressurevessels including Type 4, which is a non-metallic liner with compositeoverwrap.

One of the design challenges associated with a Type 4 pressure vessel isthe interface between the non-metallic liner and the metallic boss. Theinterface must provide a leak proof design that can withstand cyclicpressurization and depressurization over the life of the pressurevessel. Accordingly, what is needed is a boss that supports a leak proofengagement with a non-metallic liner.

BRIEF SUMMARY OF THE INVENTION

In view of the foregoing, in accordance with the invention as embodiedand broadly described herein, a method and apparatus are disclosed inone embodiment of the present invention as including a vessel (e.g., apressure vessel) comprising one or more of a liner (e.g., non-metallicliner), one or more bosses (e.g., metallic bosses), and an overwrap orshell. A liner may be substantially impermeable to the fluid to becontained within the vessel. A boss may provide a port enabling aconduit to engage a vessel and tap or replenish the fluid containedtherewithin. An interface between a liner and a boss may ensure that thevessel will not leak and will remain intact over its intended designlife. A shell may comprise various layers of filament wound over a linerand certain portions of a boss. When included, a shell may resolvecertain stresses imposed on a vessel as it is pressurized.

In selected embodiments, a boss may include an engagement flange and oneor more engagement mechanisms for securing a liner. For example, oneside of an engagement flange may include one or more engagement grooves.In certain embodiments, a boss may include an inner engagement grooveand an outer engagement groove. An O-ring groove may be positionedbetween the inner and outer engagement grooves. Accordingly, one or moreengagement grooves may provide a structural and a sealing connectionbetween a liner and a boss. Alternatively, one or more engagementgrooves may provide a structural connection, while an O-ring groove (andan O-ring contained therewithin) may provide a seal between a liner anda boss.

An insert molding process may be used to connect a boss and a liner. Insuch a process, molten plastic material may fill one or more engagementgrooves. As the plastic cools, it may hardened and lock itselftherewithin, holding the plastic tight against an O-ring positionedwithin an O-ring groove. In selected embodiments, one or more engagementgrooves may be shaped to retain the material molded therewithin. Forexample, one or more locking grooves may be undercut (e.g., having adovetail shape) and increase in width as they extend deeper into a boss.In this manner, molten material may flow into the engagement grooves.However, once the molten material hardens, it may be locked in place.

Embodiments in accordance with the present invention may be especiallywell suited for composite overwrapped pressure vessels, but may also beused for other non-reinforced non-metallic pressure vessels. Forexample, in addition to overwrapped pressure vessels handling relativelyhigh pressures of 4,500 psi to 20,000 psi or higher, there are also“low” pressure applications (e.g., applications in the range of 50 to100 psi or the like) where an overwrap may not be required. Accordingly,in such embodiments, a vessel may simply comprise a liner engaging aboss in accordance with the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing features of the present invention will become more fullyapparent from the following description and appended claims, taken inconjunction with the accompanying drawings. Understanding that thesedrawings depict only typical embodiments of the invention and are,therefore, not to be considered limiting of its scope, the inventionwill be described with additional specificity and detail through use ofthe accompanying drawings in which:

FIG. 1 is a perspective view of one embodiment of a pressure vessel inaccordance with the present invention;

FIG. 2 is a perspective, cross-sectional view of the pressure vessel ofFIG. 1;

FIG. 3 is a first, perspective view of one embodiment of a boss inaccordance with the present invention;

FIG. 4 is a second, perspective view of the boss of FIG. 3;

FIG. 5 is a partial, perspective, cross-sectional view of the boss ofFIG. 3 connected to a liner in accordance with the present invention;

FIG. 6 is a partial, side, cross-sectional view of the boss of FIG. 3connected to a liner in accordance with the present invention;

FIG. 7 is a partial, perspective, cross-sectional view of an alternativeembodiment of a boss connected to a liner in accordance with the presentinvention;

FIG. 8 is a partial, perspective, cross-sectional view of anotheralternative embodiment of a boss connected to a liner in accordance withthe present invention;

FIG. 9 is a schematic block diagram of an embodiment of a method inaccordance with the present invention; and

FIG. 10 is a schematic block diagram of another embodiment of a methodin accordance with the present invention.

DETAILED DESCRIPTION OF SELECTED EMBODIMENTS

It will be readily understood that the components of the presentinvention, as generally described and illustrated in the drawingsherein, could be arranged and designed in a wide variety of differentconfigurations. Thus, the following more detailed description of theembodiments of the system and method of the present invention, asrepresented in the drawings, is not intended to limit the scope of theinvention, as claimed, but is merely representative of variousembodiments of the invention. The illustrated embodiments of theinvention will be best understood by reference to the drawings, whereinlike parts are designated by like numerals throughout.

Referring to FIGS. 1 and 2, in describing a vessel 10 in accordance withthe present invention, it may be helpful to first establish a coordinatesystem 11. Accordingly, selected vessels 10 (or components thereof) maybe described in terms of a central axis 11 a, an axial direction 11 bextending parallel to the central axis 11 a, a radial direction 11 cextending perpendicularly away from the central axis 11 a, and acircumferential direction 11 d extending circumferentially about thecentral axis 11 a.

In selected embodiments, a vessel 10 in accordance with the presentinvention may be useful for containing a pressurized fluid. Accordingly,certain vessels 10 may be characterized as pressure vessels. A vessel 10may have any suitable shape. Suitable vessels 10 may be or include oneor more portions that are spherical, hemispherical, cylindrical,isotensoidal, geodesical, or the like or a combination orsub-combination thereof. For example, a vessel 10 may have a sphericalshape or a cylindrical shape with generally hemispherical ends. Inselected embodiments, a vessel 10 may be configured to exhibit orprovide certain desirable characteristics such as lightweightconstruction, high resistance to fragmentation, high resistance tocorrosion, and the like. In certain embodiments, a vessel 10 may be ahigh pressure composite container comprising a shell 12, liner 14, andone or more bosses 16.

In selected embodiments, a shell 12 may comprise laminated layers ofwound filaments (e.g., carbon filaments, fiberglass, syntheticfilaments, or the like) bonded together by a resin (e.g., athermal-setting epoxy resin). In use, a shell 12 may be primarilyresponsible for resolving the structural loads associated with highpressure containment. The thickness (e.g., number of layers), filamenttype, wrapping pattern, etc. of a shell 12 may be selected to provide adesired strength. This strength may include certain safety factor overthe operating pressures to be experienced by a particular vessel 10.

A liner 14 may be positioned internally with respect to a shell 12. Inselected embodiments, a liner 14 (or combined liner 14 and boss 16) mayform a mandrel about which the filaments of a shell 12 may be wound orwrapped during a manufacturing process. A liner 14 may be substantiallyimpermeable to the fluid to be contained within the vessel 10.Accordingly, a liner 14 may be primarily responsible for sealing avessel 10 and preventing internal fluids from contacting the compositematerials of the shell 12.

In selected applications or embodiments, a liner 14 may haveinsufficient strength to contain a fluid pressurized past a certain,relatively low level. Accordingly, a liner 14 may transfer (e.g., offload) all or a large portion of the loads imposed thereon by a containedfluid to a shell 10, where such loads may be resolved. A liner 14 may beformed of any suitable material or combination of materials. In certainembodiments, a liner 14 may be formed of a polymeric material,elastomeric material, or the like. For example, a liner 14 may be formedof polyethylene (PE), high density polyethylene (HDPE), polypropylene(PP), acrylonitrile butadiene styrene (ABS), or the like.

A boss 16 may join a liner 14 to a corresponding shell 12. Additionally,a boss 16 may form a port (e.g., a threaded port) enabling a conduit toengage a vessel 10 and tap or replenish the fluid contained therewithin(e.g., tap or replenish fluid contained with a liner 14). An interfacebetween a liner 14 and a boss 16 may prevent fluid from penetratingbetween the liner 14 and the shell 12. Such an interface may besufficiently robust to properly perform its desired connection andsealing functions at relatively high operating pressures of 4,500 psi to20,000 psi or higher.

In selected embodiments, a boss 16 may be a polar boss. That is, a boss16 in accordance with the present invention may be positioned proximatea pole of a vessel 10. For example, in selected embodiments, a vessel 10may have a cylindrical shape with generally hemispherical ends spaced inthe axial direction 11 b. Accordingly, a boss 16 may comprise a polarboss positioned at one of the hemispherical ends (e.g., centered withrespect to a central axis 11 b at or within a hemispherical end).

A vessel 10 may include more than one boss 16. In selected embodiments,a vessel 10 may include two bosses 16. For example, a first boss 16 maybe a first polar boss positioned at one end or pole of a vessel 10. Asecond boss 16 may be a second polar boss positioned at an opposite endor pole of the vessel 10. The first and second bosses 16 may each becentered with respect to a central axis 11 a.

A boss 16 may be formed of any suitable material. Depending on thepressures involved, suitable materials may include metals, metal alloys,polymers, ceramics, or the like. For example, in selected embodiments, aboss 16 may be machined from a single piece of aluminum or aluminumalloy. The particular alloy used may be selected to provide or balancethe desired cost, machinability, strength, hardness, or the like. Incertain embodiments, 7000 series aluminum alloys (e.g., 7175) may besuitable.

While certain situations or applications may be well suited to compositeoverwrapped pressure vessels, other situations or applications may bebetter served by other embodiments in accordance with the presentinvention. For example, there are “low pressure” applications (e.g.,fire extinguisher applications, water softener applications, etc. in therange of 50 to 100 psi or the like) where an overwrap or shell 12 maynot be required. Accordingly, in such embodiments, a vessel 10 maysimply comprise a liner 12 engaging a boss 14 in accordance with thepresent invention.

Referring to FIGS. 3-5, a boss 16 in accordance with the presentinvention may include a tubular neck 20 defining a through aperture 22.In selected embodiments, a tubular neck 20 and associated throughaperture 22 may be centered on a central axis 11 a and extend in anaxial direction 11 b defined thereby. When a vessel 10 is assembled orformed, a through aperture 22 of a boss 16 may correspond to or bealigned with an aperture 24 in a liner 14. Accordingly, fluid may passthrough a through aperture 22 when entering or exiting a vessel 10.

A surface 26 defining a through aperture 22 may have any suitableconfiguration. In selected embodiments, such a surface 26 may begenerally cylindrical in shape. The surface may be substantially smooth.Alternatively, the surface 26 may be configured to support engagementwith one or more conduits, valves, or the like. For example, in selectedembodiments, the surface 24 (or some portion thereof) may be threaded.

A surface 28 defining an exterior of a tubular neck 20 may have anysuitable configuration. In selected embodiments, such a surface 28 maybe configured to support engagement with one or more conduits, valves,or the like. For example, in selected embodiments, the surface 28 (orsome portion thereof) may include one or more flats 30 supportingengagement with wrench, clamp, or the like. Alternatively, the surface28 may include threads.

In certain embodiments, a boss 16 may include an engagement flange 32.An engagement flange 32 may extend radially from and circumferentiallyabout one end (e.g., an internal or proximal end) of a tubular neck 20.A boss 16 may also include one or more engagement mechanisms 34. Eachsuch engagement mechanism 34 may engage or secure a correspondingengagement mechanism 36 of a liner 14. For example, complementaryengagement mechanisms 34, 36 may provide a secure structural interfacebetween a liner 14 (e.g., non-metallic liner) and a dissimilar boss 16(e.g., metallic boss) that will remain intact over the life of a vessel10.

In selected embodiments, one or more engagement mechanisms 34 of a boss16 may be positioned on an engagement flange 32. For example, an outeredge 34 a or circumference 34 a of an engagement flange 32 may extendinto (e.g., be overlapped in the axial direction 11 b by) a portion 36 aof a liner 14. Accordingly, the outer edge 34 a may form an engagementmechanism 34 of a boss 16 and the overlapping portion 36 a may form anengagement mechanism 36 of a liner 14.

Alternatively, or in addition thereto, an engagement flange 32 mayinclude one or more engagement grooves 34 b, 34 c or groove segmentsforming one or more engagement mechanisms 34. Such grooves 34 b, 34 cmay be shaped to retainer the liner material applied thereto. Forexample, in selected embodiments, one or more engagement grooves 34 b,34 c may be undercut (e.g., have a dovetail cross-section or an increasein width with an increase in depth). Accordingly, in a formation orassembly process, molten liner material may freely flow into anengagement groove 34 b, 34 c. However, once that material hardens, itmay resist removal (e.g., removal in the axial direction 11 b) from theengagement groove 34 b, 34 c. Thus, the hardened material 36 b, 36 c mayform an engagement mechanism 36 of a liner 14.

In selected embodiments, one or more engagement grooves 34 b, 34 c maybe formed on one or more sides of an engagement flange 32. For example,one side (e.g., an interior or proximal side) of an engagement flange 32may include one or more engagement grooves 34 b, 34 c extendingcontinuously in the circumferential direction 11 d around a throughaperture 22. In certain embodiments, two such grooves (e.g., an outerengagement groove 34 b and an inner engagement groove 34 c) may extendcontinuously in the circumferential direction 11 d around a throughaperture 22.

In selected embodiments, one or more seal or O-ring grooves 38 may beformed on one or more sides of an engagement flange 32. For example, oneside (e.g., an interior or proximal side) of an engagement flange 32 mayinclude one or more O-ring grooves 38 extending continuously in thecircumferential direction 11 d around a through aperture 22. In certainembodiments, one or more O-ring grooves 38 may be positioned proximateone or more engagement grooves 34 b, 34 c. For example, a boss 16 maycomprise a single O-ring groove 38 positioned between inner and outerengagement grooves 34 b, 34 c. Accordingly, one or more engagementgrooves 34 b, 34 c may provide a structural connection with a liner 14,while an O-ring groove 38 (in conjunction with an O-ring 40 containedtherewithin) may assist in providing a seal between a liner 14 and aboss 16.

A boss 16 may include one or more features 42 (e.g., one or moreextensions 42, indentations 42, or the like) resisting rotation of theboss 16 with respect to a corresponding liner 14. For example, inselected embodiments, an engagement flange 32 may include one or moreextensions 42. Accordingly, as a liner 14 is applied (e.g., molded onto)a boss 16, the material of the liner 14 may surround, fill, etc. thefeatures 42 and, once hardened, resist relative rotation (e.g., rotationabout a central axis 11 a) between a liner 14 and boss 16.

Referring to FIG. 6, in selected embodiments, during a formationprocess, molten material forming a liner 14 may surround or abut oneside of an O-ring 40 (e.g., a side facing away from an O-ring groove38). For example, molten material may enter a portion of an O-ringgroove 38. The amount of material entering may depend on the formationprocess. For example, less material may enter when a liner 14 is formedin a roto-molding process than when a liner 14 is formed in an injectionmolding process. In selected embodiments, the material entering aportion of an O-ring groove 38 or abutting an O-ring 40 may assist insealing a liner 14 with respect to a boss 14.

In certain embodiments, pressure 44 within a vessel 10 may assist inmaintaining a seal between a liner 14 and a boss 16. In selectedembodiments, internal pressure 44 may urge, seat, or maintain a portionof a liner 14 firmly seated against an O-ring 40. For example, on aninterior side 46 of an O-ring 40, a seam between a liner 14 and a boss16 may be pressurized to substantially the same pressure as the interiorof the liner 14. The interior pressure 44 may oppose or balance thisseam pressure and resist the separation that such seam pressure mayotherwise induce.

Additionally, on an exterior side 48 of an O-ring 40, a seam between aliner 14 and a boss 16 may be at ambient pressure. With the interiorpressure 44 being larger (e.g., much larger) than ambient pressure, theinterior pressure 44 may bias the liner 14 or a portion thereof firmlyagainst the boss 14 along the seam on the exterior side 48. This biasmay extend to the seal created by the O-ring 40. Thus, the bias may urgethe liner 14 firmly against the O-ring 40.

In certain embodiments, pressure on an interior side 46 may compress 50an O-ring 40, urging it toward the exterior side 48. This compression 50in one direction may, in turn, urge an expansion 52 of an O-ring 40 inanother direction (e.g., in an orthogonal direction). This urgedexpansion 52 may assist in seating an O-ring 40 with sufficient force toproduce the desired seal. Alternatively, or in addition thereto, theurged expansion 52 acting against the internal pressure 44 may assist inseating an O-ring 40 with sufficient force to produce the desired seal.Accordingly, certain vessels 10 in accordance with the present inventionmay have burst pressures up to about 30,000 psi or higher.

An O-ring 40 in accordance with the present invention may be formed ofany suitable material. A suitable material may be selected to provide adesired strength, spring constant, resilience, hardness, durability,chemical resistance, operable temperature range, or the like. Inselected embodiments, an O-ring 40 formed of polytetrafluoroethylene(PTFE), Buna-N, some other rubber compound, silicone, or the like may besuitable.

Referring to FIG. 7, engagement mechanisms 34 in accordance with thepresent invention may have any suitable shape, positioning, orconfiguration. As set forth hereinabove, a boss 16 may include one ormore engagement mechanisms 34 configured as engagement grooves 34 b, 34c located on a side of an engagement flange 32. Alternatively, or inaddition thereto, a boss 16 may include an engagement groove 34 d,recess 34 d, or axial undercut 34 d formed within a through aperture 22.

Referring to FIG. 8, in selected embodiments, a liner 14 may beconfigured to support selective attachment and detachment from a boss16. Accordingly, a liner 14 may first be formed and then later attachedto a boss 17. This may be beneficial when certain processes associatedwith forming a liner 14 may be incompatible with or adverse to a boss16. For example, in selected embodiments, a boss 16 may be heat treatedto provide certain desirable properties. Connecting such a boss 16 witha liner 14 in an insert molding process (e.g., a rotomolding process)may expose the boss 16 to heat that may disrupt or “erase” the heattreatment and the desirable properties associated therewith.

A liner 14 may be selectively attached to or detached from a boss 16 inany suitable manner. For example, in selected embodiments, a portion 34e of a through aperture 22 may be threaded. A corresponding portion 36 eof a liner 14 may be similarly threaded. Accordingly, in an assemblyprocess, a liner 14 may be threaded into or onto a boss 16. In suchembodiments, an overlapping portion 36 a of a liner 14 (e.g., as seen inFIG. 7) may be omitted, leaving no obstruction to threading the liner 14into or onto a boss 16.

Referring to FIG. 9, vessel 10 in accordance with the present inventionmay be formed by any suitable method. In selected embodiments, theformation of a vessel 10 may include an insert molding process. Forexample, a method 54 of forming a vessel 10 may begin with obtaining 56a boss 16 in accordance with the present invention. The boss 16 may thenbe prepared 58. Such preparation may include texturing, cleaning, or thelike. For example, in selected embodiments, one or more surfaces of aboss 16 that will contact a liner 14 may be roughened or textured in asand-blasting process. The boss 16 may then be cleaned to remove anydebris, particles, oils, or the like to promote proper adhesion.

Once a boss 16 has been prepared 58, an O-ring 40 may be positioned 60within the boss 16 (e.g., within an appropriate groove 38 of the boss16). An O-ring 40 may be held within a corresponding groove 38 in anysuitable manner. In selected embodiments, one or more of a groove size,O-ring size, O-ring material, or the like may be selected to ensure thatan O-ring 40 is self-securing and will not inadvertently fall out ofplace. A boss 16 may then be placed 62 or positioned 62 within anappropriate mold. A liner 14 may be formed and connected to a boss 16 inan insert molding step 64 or sub-process 64. This molding step 64 may beof any suitable type, including roto-molding, injection molding, blowmolding, etc.

With the completion of a molding step 64, a combined liner 14 and boss16 may be removed from a mold and used in certain “low pressure”applications. Alternatively, a composite overwrap may be applied 66 tothe combined liner 14 and boss 16, which may produce a vessel 10 capableof containing significant pressures.

Referring to FIG. 10, in selected embodiments, the formation of a vessel10 may not include an insert molding process. For example, analternative method 68 of forming a vessel 10 may begin with obtaining 56a boss 16 and obtaining 70 a liner 14. A liner 14 may be obtained (e.g.,formed) in any suitable process. For example, in certain embodiments, aliner 14 may be formed in a roto-molding, injection molding, or blowmolding process.

An O-ring 40 may be positioned 60 within the boss 16 (e.g., within anappropriate groove 38 of the boss 16). The boss 16 may then be applied72 to the liner 14. For example, the liner 14 may be threaded or snappedonto or into the boss 16. A combined liner 14 and boss 16 may be used incertain low pressure applications. Alternatively, a composite overwrap12 may be applied 66 to the combined liner 14 and boss 16.

It should be noted that, in some alternative implementations, thefunctions noted in the blocks may occur out of the order noted in FIGS.9 and 10. In certain embodiments, two blocks shown in succession may, infact, be executed substantially concurrently, or the blocks maysometimes be executed in the reverse order, depending upon thefunctionality involved. For example, in FIG. 9, the positioning 60 of anO-ring 40 may occur after a boss 16 has been positioned 62 within amold. Alternatively, certain steps or functions may be omitted if notneeded. For example, in certain embodiments, the step of applying 66 anoverwrap 12 may be omitted.

The present invention may be embodied in other specific forms withoutdeparting from its spirit or essential characteristics. The describedembodiments are to be considered in all respects only as illustrative,and not restrictive. The scope of the invention is, therefore, indicatedby the appended claims, rather than by the foregoing description. Allchanges which come within the meaning and range of equivalency of theclaims are to be embraced within their scope.

What is claimed and desired to be secured by United States LettersPatent is:
 1. A method of manufacturing a pressure vessel, the methodcomprising: positioning a boss as an insert within a mold, the bosscomprising a through aperture, a first groove encircling the throughaperture, an engagement mechanism, and an O-ring positioned within thefirst groove; molding, within the mold after the positioning, apolymeric container such that a portion of the polymeric container ismolded directly against the O-ring; the molding comprising engaging, bypolymeric material of the polymeric container, the engagement mechanismto secure the polymeric container to the boss; and removing, after themolding, the boss and polymeric container as a unit from the mold. 2.The method of claim 1, further comprising wrapping, after the removing,the polymeric container and at least a portion of the boss with acomposite material.
 3. The method of claim 1, wherein: the O-ring has aconvex surface; and the molding further comprises forming the polymericmaterial to abut and substantially match the convex surface of theO-ring.
 4. The method of claim 1, wherein: the engagement mechanismcomprises a first undercut cavity formed in the boss; and the moldingfurther comprises filling the first undercut cavity with the polymericmaterial.
 5. The method of claim 4, wherein: the engagement mechanismfurther comprises a second undercut cavity formed in the boss; and themolding further comprises filling the second undercut cavity with thepolymeric material.
 6. The method of claim 5, wherein the first undercutcavity comprises a second groove encircling the through aperture.
 7. Themethod of claim 6, wherein the second undercut cavity comprises a thirdgroove encircling the through aperture.
 8. The method of claim 7,wherein the first, second, and third grooves are concentric.
 9. Themethod of claim 8, wherein the second groove is interior to the firstgroove.
 10. The method of claim 9, wherein the first groove is interiorto the third groove.
 11. A method of manufacturing a pressure vessel,the method comprising: positioning a boss as an insert within a mold,the boss comprising a through aperture, a first groove encircling thethrough aperture, an engagement mechanism, and an O-ring positionedwithin the first groove; molding, within the mold after the positioning,a liner to have an interior surface and an exterior surface, theinterior surface defining an interior cavity of the pressure vessel; themolding comprising molding the exterior surface directly against theO-ring; the molding further comprising engaging, by material of theliner, the engagement mechanism to secure the liner to the boss; andwrapping, after the molding, the liner and at least a portion of theboss with a composite material.
 12. The method of claim 11, wherein: theboss comprises a flange extending radially away from the throughaperture, the flange having a first side facing a first direction and asecond side facing a second direction substantially opposite to thefirst direction; and the first groove is formed in the first side of theboss.
 13. The method of claim 12, wherein the engagement mechanismcomprises a first undercut cavity formed in the first side of the boss;and the molding further comprises filling the first undercut cavity withthe polymeric material.
 14. The method of claim 13, wherein: theengagement mechanism further comprises a second undercut cavity formedin the first side of the boss; and the molding further comprises fillingthe second undercut cavity with the polymeric material.
 15. The methodof claim 14, wherein the first undercut cavity comprises a second grooveencircling the through aperture.
 16. The method of claim 15, wherein thesecond undercut cavity comprises a third groove encircling the throughaperture.
 17. The method of claim 16, wherein the first, second, andthird grooves are concentric.
 18. The method of claim 17, wherein thesecond groove is interior to the first groove.
 19. The method of claim18, wherein the first groove is interior to the third groove.
 20. Amethod of manufacturing, the method comprising: positioning an insertwithin a mold, the insert comprising a metal component, a groove formedin the metal component, an engagement mechanism, and a seal componentpositioned within the first groove; molding, within the mold after thepositioning, a polymeric component such that a portion of the polymericcomponent is molded directly against the sealing component; the moldingcomprising engaging, by polymeric material of the polymeric component,the engagement mechanism to secure the polymeric container to the boss;removing, after the molding, the metal component and the polymericcomponent as a unit from the mold; and sealing, by the sealingcomponent, an interface between the metal component and the polymericcomponent.